1. Field of the Invention
The present invention generally relates to image forming apparatuses capable of printing on index sheets, and particularly relates to an image forming apparatus and an image processing program which are capable of proper printing on index sheets by avoiding inconsistency between the printing orientation and the index direction.
2. Description of the Related Art
Widespread use of DTP (desktop publishing) facilitated by the spread of personal computers is not only changing household activities but also the type of work that is conducted at office. In the conventional process of bookbinding, a fully bound book will not be available for a number of days after requesting bookbinding to a bookbinder. Image forming apparatuses are nowadays connected to peripheral devices capable of bookbinding, and can take care of a front cover, chapter delimiters, stapling, and punching, providing a fully bound book on the spot.
In such bookbinding by image forming apparatuses, it is well known to insert chapter-separating sheets (e.g., see Japanese Patent Application Publication No. 2001-278530). If an tab-index sheet having a tab projecting from a standard-size sheet is used as a chapter-separating sheet, readers can easily find the chapter that the readers wish to read.
A tab-index sheet, however, is generally comprised of a standard-size sheet and a tab projecting from this standard-size sheet, as described above. In most image forming apparatuses of the conventional art, the projecting tab needs to be situated on the rear side when the sheet is carried inside the apparatus.
This is because the printing method of conventional image forming apparatuses requires such positioning. When images are to be printed on sheets, generally, the front end of the sheets being conveyed are aligned with the front tip of the images. To this end, image forming apparatuses conveys the sheets such that the front end of the sheets being conveyed is struck against the resist rollers, thereby compensating for skews generated during the conveyance of the sheets and carrying out printing at proper timing.
If a tab is situated at the front end in such a printing scheme as described above, image forming apparatuses would have difficulty aligning the front tip of images to the front end of tab-index sheets unless special equipment is provided. Accordingly, tabs are always positioned at the rear end when tab-index sheets are conveyed.
When a sheet that is horizontally or vertically asymmetrical because of the indexing tab is used, an orientation in which an image is printed should be taken care of. If the tab should come at the top right corner of an image, the image should be printed in such a position.
Image forming apparatuses ate generally provided with a function to rotate a scanned image when printing the image. If a A4 document sheet is set in a vertical position as viewed from the user, and if a A4 print sheet is set in a horizontal position in an image forming apparatus, for example, the image scanned in the vertical position can be rotated to be in a horizontal position so as to match the position of-the print sheet.
The rotation of an image may be set to 0 degree, 90 degrees, 180 degrees or 270 degrees if there are no particular limitations.
In general, the rotational angle of an image is determined based on an algorithm that takes into account an operation mode relating to a document size, sorting, stacking, tray selection, etc.
Conventional image forming apparatuses do not take into account the orientation of an image relative to an indexing tab such as when the tabs come at the right-hand-side edge of the book that is bound on the left-hand-side edge.
Further, a problem arises when the direction of the indexing tab does not match the position of stapling or the position of punching as in the case in which the orientation of printed images is limited by stapling or punching.
Moreover, conventional image forming apparatuses do not match the orientation of images with the orientation of the first image at the time of printing by using the first image of a document as a reference. Because of this, images printed on different pages may be oriented in different directions, thereby making it difficult to bind the book after printing.
Accordingly, there is a need for an image forming apparatus and an image processing program which can properly set the orientation of images so as to make it match the direction of a tab of a tab-index sheet.